Making the quality of PVRTC textures higher

-

Introduction

When developing mobile games many people face the need of reduction the occupied memory or the size of distributive. They are textures, which are the largest assets in most projects. 1024x1024 uncompressed texture sizes about 4 Mb generally. And usually there is more than one texture in a scene. We have to compress textures if we really want to reduce memory usage and make the loading process of the scenes much faster. We are going to use PVRTC as an example. This algorithm has its own advantages as well as disadvantages. While texture size is reduced by 8 times, terrible artifacts show up, especially in transparent textures. This post is written to help when struggling with those artifacts.

Method

The main point of this method is the post-processing a texture before compressing it. To do this we need any graphics editing program that supports layers. I used Adobe Photoshop.
Let’s consider the algorithm in details:
1) Open your texture with Photoshop.
2) Create a new layer on the top of existing one.


3) Fill it with medium gray color like in the picture: 



4) Add noise to this layer (Filter -> Noise -> Add Noise… ) with the following settings:



5) Set the Blend Mode as “Soft Light” and change the value of opacity from 30 to 50 percent so that the noise is not too explicit, but still visible.



6) Save your texture and import it to the project. 



If you have a transparent texture – after selecting pixels from the source layer invert the selection and remove the pixels from noisy layer.



Then specify “RGBA Compressed PVRTC 4bit” from the list of compression algorithms in editor’s texture importer.

I strongly recommend you to check “Override” option in iOs and Android tabs and select “Best” in Compression Quality. If your texture is going to be used for GUI, unchecked the “Generate Mip Maps” option to prevent the blur effect in case the texture is far from the camera.


Results



Conclusion

Before I used this simple method I had to leave uncompressed textures for GUI in the project, which was not good because the application took a lot of memory space. With this approach everybody can compress almost all GUI textures, except the ones with large amount of small details. Those textures we still have to place into individual atlases with no compression. However, memory savings in this case are rather notable.

Special Thanks to Nikita Zakharchenko
Senior Unity Developer

Comments

Post a Comment

Popular posts from this blog

Texture compression is Efficiency key for mobile graphics

-
Image
Texture compression technology has been developed to provide significant enhancements in quality and efficiency offering application developers the required performance and quality at 2bpp and 4bpp resolutions while lowering system memory usage and reducing GPU processing overhead for the low power-driven world of mobile graphics. Textures are ubiquitous in mobile and desktop graphics. They add a degree of realism to a wide range of applications like games or navigation apps where a combination of factors such as image quality and loading times are vital to smartphone, tablet and portable console users. Typically such content is increasingly pushing for higher quality on higher resolutions in order to raise the overall quality bar. This means computing systems need to have access to the right combination of features, raw graphics and compute performance and software tools to make efficient use of all available resources. Memory, quality, power, performance: the four horsemen of te...
Read more

Pixel vs. Texel

-
Image
Digital images are composed of dots arranged on a grid. Each of these little dots is called a pixel, a contraction of the term 'picture element'. The same is true of the texture graphics that get drawn onto polygons in 3D games; a Texel simply a pixel within a texture image. Pixel is the fundamental unit of screen space. Texel, or texture element (also texture pixel) is the fundamental unit of texture space. Textures are represented by arrays of Texels, just as pictures are represented by arrays of pixels. When texturing a 3D surface (a process known as texture mapping) the renderer maps Texels to appropriate pixels in the output picture. Between, it is more common to use fill rate instead of write speed and you can easily find all required information, since this terminology is quite old and widely-used. As part of their performance specifications, graphics cards often describe how many Texels they can process each second. This is their texture fill rate: the num...
Read more

How mobile apps and games make money?

-
Image
Once you have a good idea for a game or app it’s important to stop and think about  how to make enough money to at least cover what  you've  invested to create it. While there are as many ways to make money from an application as one can imagine, in this Post we will discuss the most common  business models for apps and games , using some models of well-known apps and games as examples. I hope you find this helpful as you create your own app! In app purchase from CSR Racing In app purchase from Clash of Clans     Free Apps + Advertising:   Free download with income  via banners and ads ( iAd ,  AdMob , millennial media, place play) Apps published through this format often have a double objective: one, to generate income through impression and ad-banner clicks, and two, to serve as an app or game demo that later has a paying version. Example: Angry bird free iAd could pay between  $.30 and $3.00 for eCPM ...
Read more